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A blowhole is also the name of a rare geologic feature in which air is blown through a small hole at the surface due to pressure differences between a closed underground system and the surface. The blowholes of Wupatki National Monument are an example of such a phenomenon. It is estimated that the closed underground passages have a volume of at ...
The formation of this harbour has occurred due to active erosional processes on an extinct shield volcano, whereby the sea has flooded the caldera, creating an inlet 16 km in length, with an average width of 2 km and a depth of −13 m relative to mean sea level at the 9 km point down the transect of the central axis. [5]
In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than 2 km (1.2 mi) [1] or 5 km (3.1 mi) [2] [3] above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the overriding plate in active subduction zones.
The Pancake Rocks are a heavily eroded limestone formation where the sea bursts through several vertical blowholes during incoming swells, particularly at high tide. The limestone was formed in the Oligocene period (around 22–30 million years old), a period in the geological history of New Zealand where most of the continent of Zealandia was submerged beneath shallow seas. [2]
A geo or gio (/ ɡ j oʊ / GYOH, from Old Norse gjá [1]) is an inlet, a gully or a narrow and deep cleft in the face of a cliff. Geos are common on the coastline of the Shetland and Orkney islands. They are created by the wave driven erosion of cliffs along faults and bedding planes in the rock. Geos may have sea caves at their heads. Such sea ...
Wind erosion of soil at the foot of Chimborazo, Ecuador Rock carved by drifting sand below Fortification Rock in Arizona (Photo by Timothy H. O'Sullivan, USGS, 1871). Aeolian processes, also spelled eolian, [1] pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets).
Orogenic uplift is the result of tectonic-plate collisions and results in mountain ranges or a more modest uplift over a large region. Perhaps the most extreme form of orogenic uplift is a continental-continental crustal collision. In this process, two continents are sutured together, and large mountain ranges are produced.
One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. [2] The alternative plate theory is that the mantle source beneath a hotspot is not anomalously hot, rather the crust above is unusually weak or thin, so that lithospheric extension permits the passive rising of melt from shallow ...